Round counter for firearm

ABSTRACT

A round counter for a firearm is provided that includes a display that provides the user with information regarding the number of rounds remaining in the magazine of the firearm. The magazine includes a round follower and a wiper extending from the follower. The wiper contacts a variable resistance sensor, such as a linear potentiometer, that is attached to a sidewall of the magazine. As the round follower and wiper move up and down within the magazine, the wiper contacts the sensor at different positions. The position of the wiper relative to the sensor corresponds to a specific linear distance indicative of the number of rounds remaining in the magazine. Information regarding this position, and consequently the number of remaining rounds is transmitted to the display.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/340,282 filed May 23, 2016, the entire content of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the magazine of a firearm. In particular, the present invention relates to a counter for determining the number of rounds remaining in the firearm magazine.

BACKGROUND OF THE INVENTION

Existing reciprocating bolt firearms, including carbines and rifles, such as the AR15/M16 among others, employ a magazine to store unfired rounds of ammunition in a queue to be fired by the rifle. For many applications, including competitive shooting, law enforcement combat and others, it is critical for the firearm shooter to know how many rounds remain in the magazine. However, many magazines as currently used give no indication of the remaining rounds. The shooter is forced to either keep a mental count of how many rounds have been fired or be prepared for the firearm to cease firing unpredictably, preventing the operator from reloading the firearm at a strategically advantageous time.

BRIEF DESCRIPTION OF THE FIGURES

Advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. The figures identified here represent various features in accordance with embodiments of the present invention.

FIG. 1 is a cutaway schematic view of a firearm magazine.

FIG. 2 is a schematic view of a display assembly.

FIG. 3 is a schematic view of a firearm magazine and sensor.

FIG. 4 is a schematic view of an electronics compartment.

FIG. 5 is a view of the top of a firearm magazine.

FIG. 6 is a perspective view of a firearm magazine.

FIG. 7 is a view of the side of a firearm magazine.

FIG. 8 is a view of the rear of a firearm magazine.

FIG. 9 is an exploded, perspective view of a firearm magazine.

FIG. 10 is a view of the rear of a firearm magazine.

FIG. 11 is a cut-away view of a firearm magazine along the line B-B of FIG. 10.

FIG. 12 is a detail view of section C of FIG. 11.

FIG. 13 is a perspective view of a display assembly.

FIG. 14 is a cut-away, perspective view of a firearm magazine.

FIG. 15 is a cut-away view of the side of a firearm magazine.

FIG. 16 is a perspective view of a display assembly.

FIG. 17 is a cut-away, perspective view of a firearm magazine.

FIG. 18 is a cut-away view of the side of a firearm magazine.

FIG. 19 is an exploded, perspective view of membrane potentiometer.

FIG. 20 is a cross-sectional, schematic view of membrane potentiometer.

DETAILED DESCRIPTION

Throughout this application, the directional references, such as forward, rearward, left, right, bottom and top, will be used. These and other such references are relative to the firing direction of the firearm, which fires in a forward direction. Such references are used for ease in describing the present invention and should not be construed as limiting the scope of the invention. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” Also, reference designators shown herein in parenthesis indicate components shown in a figure other than the one being discussed.

This application may make reference to an AR-15 patterned rifle and include illustrations of magazine embodiments appropriate for use with such a rifle. However, it will be understood by one of ordinary skill in the art that the principles of the present invention are applicable to a broad range of firearms using round storing magazines, including rifles, handguns, shotguns, etc. The present invention should not be understood to be limited to use with an AR-15 patterned rifle or any other particular firearm.

The embodiments of the invention are designed to incorporate into a rifle's magazine, intended for use in the AR-15 patterned rifle. The basic function will read the follower's location inside the magazine body in order to calculate the number of cartridges in the magazine and display that information to the shooter, for example by means of a small LCD screen or some other appropriate display device.

This device uses a thinpot linear potentiometer affixed within the magazine body. The magazine follower contains a spring plunger to impart pressure to the linear potentiometer. The potentiometer is arranged vertically, against the rear interior wall of the magazine body. The spring plunger is oriented horizontally, at the rear of the follower, and protrudes beyond the follower's rear edge. Pressure applied to the potentiometer by the plunger creates a contact patch within the potentiometer's structure. This depression effectively changes measured resistance within the potentiometer. Thus, the location of that contact patch may be interpreted by the digital processor. The potentiometer directly produces analog data that is converted into a digital format by an analog/digital converter.

The magazine body contains a magnetic switch to control power supply to the onboard sensors and processors. The magnetic switch is located on the rear external surface of the mag body, that when the magazine is locked into the rifle, is adjacent to the trigger guard in the rifle receiver. The trigger guard contains a permanent magnet that closes the switch and “turns on” or provides an initiation signal to the electronic systems when the magazine is in place.

The analog converter, digital processor, and power source are housed within the floorplate structure of the magazine and are hard wired for power and data transmission within the magazine. The digital processor communicates with the user display by radio frequency (“RF”), Bluetooth or Wifi signal.

FIG. 1 shows a cut-away schematic view of a firearm magazine in accordance with embodiments of the present invention. The magazine 100 stores rounds 102 of ammunition for use in the firearm. A round follower 104 is positioned within the magazine below the rounds 102. A magazine spring 106 is positioned below the round follower 104 and applies an upward spring force on the round follower such that as each round is loaded into, fired and ejected from the firearm, the following round is pushed upward into a position that it can be engaged and loaded into the firearm firing chamber.

A contact sensitive variable resistance sensor 108 is positioned within the magazine 100. In the illustrative embodiment, the resistor extends vertically along a rear sidewall 110 of the magazine. The sensor 108 may be any appropriate variable resistance sensor. In embodiments, the sensor may be a potentiometer. In further embodiments, the sensor may be a linear potentiometer. For example, embodiments may use a membrane potentiometer such as ThinPot potentiometer manufactured by Spectra Symbol.

As shown in FIGS. 19-20, embodiments of the sensor 108 may be a membrane potentiometer 1080 may include a top circuit 1082, a circuit spacer 1084, a bottom circuit 1086 and a bottom adhesive layer 1088. The potentiometer 1080 may be a three-wire system with two resistive output channels and an electrical collector channel. By pressing a wiper 1089 down onto the top circuit 1082 the potentiometer produces the desired electrical output. The wiper 1089 is a non-conductive mechanism that depresses the top circuit 1082 actuating the potentiometer from the outside of the element.

The top 1082 and bottom 1086 circuits are separated by a spacer 1084. The spacer may comprise 0.15 mm (0.006″) of adhesive build-up. Contact between the circuits occurs by pressure from the wiper 1089 on the top circuit 1082, pushing down until the top circuit connects with the bottom circuit 1086 to create a potentiometric output. The required pressure may be between 1-3 Newtons. The potentiometer 1080 may also include a layer of adhesive 1088 that allows the potentiometer to be adhered to a surface.

Returning to FIG. 1, the sensor 108 is adhered to an inner surface 112 of the rear sidewall 110 of the magazine 100. A wiper 114 that may comprise a stylus or plunger extends from a rear portion of the round follower 104 and contacts the sensor 108 with sufficient pressure to activate the sensor. The wiper may be made of any appropriate material, including metal, plastic or other materials as would be apparent to one of ordinary skill in the art. The wiper may be spring loaded to provide the appropriate pressure to the sensor 108.

The magazine 100 may also include electronics compartment 116 that encloses electronics components. The electronics compartment is shown positioned adjacent a bottom wall 117 of the magazine, but the compartment could be positioned in other locations within the magazine, for example: along a magazine side wall, within or attached to the round follower 104 or inside the spring 106 coil.

Magazine 100 may also include an identification tag 119. The tag 119 may be encoded with a unique serial or identification number. The unique number may be used to identify the particular magazine for communications with the display assembly as described below. The tag 119 may be mounted on an exterior surface of the magazine, may be housed within the electronics compartment 116, including being attached to or integrally formed with electronics components, may be embedded within the magazine body (170) or may be positioned in another location on the magazine. The tag may contain optically readable information, such as a barcode or 2D barcode. Alternatively, the tag may comprise active radio or other transmission, or the tag may comprise a passive RFID tag. Identifying information provided by the tag may be permanently or persistently stored or may be generated by components of the magazine as needed to enable identification of the magazine.

FIG. 3 shows a schematic view of the sensor 108 and wiper assembly 114. As discussed above, the magazine includes a wiper assembly 114 that may comprise a spring loaded plunger or stylus 118. The stylus 118 contacts the sensor 108, which may be a position sensitive variable resistance sensor. The sensor may include various electric connections. A power connection 120 may provide an appropriate voltage to operate the sensor. A ground connection 122 may connect the sensor to ground, and an output signal connection 124 may provide for the sensor to send a signal containing information regarding the position of the wiper 114 relative to the sensor and therefor relative to the round follower's position within the magazine. These signals may include an analog electrical signal that is proportional to the position of the wiper.

FIG. 4 shows a schematic view of components that may be included in the electronics compartment 116. The compartment may include an analog to digital converter (“ADC”) 126. The converter may have an input connection 128 that receives signals provided on the output connection 124 of the sensor 108. The ADC converts an analog signal received from the sensor 108 into digital information. The digital information can then be sent on an output connection 134 of the ADC. The ADC may also include a power connection 130 and a ground connection 132.

The electronics compartment 116 may also contain a digital signal processor (“DSP”) 136. The DSP receives the digital information output by the ADC and converts the information into a signal that is suitable for transmission to a display capable of being read by the shooter. The DSP then outputs the digital signal on an output connection 138. The DSP may also include a power connection 140 and a ground connection 142.

The electronics compartment 116 may also contain a transmitter 144. The transmitter receives the signal from the DSP 136 and transmits it to a display capable of being read by the shooter. The transmitter may use any of a variety of appropriate transmission methods and may include the necessary circuitry for using those transmission methods. For example, the transmitter may be a low power radio frequency transmitter, or the transmitter may use other communications protocols, including Bluetooth, WiFi or infrared. Alternatively, the transmitter may employ near field communication, with the transmitter 144 being the non-powered/read side of communication protocol. The transmitter 144 may include an antenna 146 appropriate to the transmission protocol being used. The transmitter 144 may also include a power connection 148 and a ground connection 150.

The electronics compartment 116 may further include a battery 152 or other power source that provides electrical power to the power connections 130, 140, 148 of the sensor 108, ADC 126, DSP 136, transmitter 144 and other components. In the schematic view of FIG. 4, the components of the electronics compartment are shown positioned adjacent to one another. However, it will be understood the various components, while in electronic/electrical connection, may be positioned at different locations within the magazine or firearm.

FIG. 2 shows a schematic view of a display assembly 160 that may be used in embodiments of the present invention. The display assembly 160 may include a receiver 154 that receives information sent from the transmitter 144 of the magazine 100. The receiver may include an antenna 156 appropriate to the transmission protocol being used. The display assembly 160 may further include a display driver 158 and a display 162 that is capable of being read by the shooter. The display assembly 160 may further comprise a battery (not shown) to provide electrical power to the components of the display assembly.

The display 162 may comprise any appropriate display mechanism. For example, the display may comprise an LCD or LED screen. Alternatively the display may comprise an seven-segment display. The display may numerically display the number of rounds remaining in the magazine or it may display a gauge, bar graph or the like indicating the absolute or relative number of rounds remaining. The display may be configured to convey additional information beyond the number of rounds in the magazine.

The display may be located anywhere on the firearm that is visible to the shooter. The display may be positioned adjacent to a sighting device of the firearm or it may be positioned on a surface of the firearm's action, grip, barrel, etc. The display may be a separate component attached to a surface of the firearm or it may be integrated into the body of the firearm. Alternatively, the display may project the information to be displayed into the sighting optics of the firearm in the manner of a heads-up display.

The components of the display assembly may be contained in a single enclosure, or they may be dispersed over various locations on the firearm. For example, the receiver 154, display driver 158 and display 162 may be positioned together adjacent to a rear sight of the firearm while the battery is positioned in a grip or stock of the firearm.

FIGS. 5-9 show a firearm magazine in accordance with the present invention. The magazine 100 is inserted into the receiver of a firearm. A latch 172 engages the receiver and retains the magazine in connection with the firearm. The magazine includes a magazine body 170 with a rear sidewall 110. Rounds of ammunition are inserted into an opening 174 at the top end of the magazine. As the rounds are inserted a round follower 104 is pushed downward within the magazine. The round follower comprises a plunger 118 that contacts a sensor 108. The plunger 118 is held against the sensor by a spring 176.

The sensor 108 is positioned inside the magazine against an inner surface of the rear sidewall 110 such that the plunger 118 is held in contact with different portions along the length of the sensor as the round follower 104 moves up and down within the magazine in response to loading the magazine and firing the firearm. The sensor includes a wiring lead 188 that may include connectors for power 120, ground 122 and transmission 124.

The magazine includes a bottom wall 117. The magazine may include a groove 178 formed adjacent to the bottom wall of the magazine. The groove 178 may engage a finger or extension 180 formed adjacent to the top surface 182 of an electronics compartment 116 such that the electronics compartment can be slidably engaged with the magazine body 170. The electronics compartment 116 may house a battery 152, an ADC 126, a DSP 136 and a transmitter 144. These elements may comprise separate electronic components or two or more elements may be combined into a single electronic component. The electronics component may include a removable rear wall 184 that allows access to the components positioned within the electronics compartment 116.

The magazine may further comprise a reed switch 186 that is positioned along the rear sidewall 110 of the magazine body 170. The reed switch may serve as an interrupt that signals to the electronic components of the magazine when the magazine has been installed into a firearm. For example, a compatible firearm may have a permanent magnet, for example a rare earth magnet installed in a forward portion of the trigger guard such that the magnet is adjacent to the reed switch when the magazine is installed. When the magazine is installed, the reed switch is activated and a signal is sent to one or more electronic components of the magazine indicating that the magazine is in place in a firearm. Alternatively, the reed switch may be used to close a power circuit within the magazine, providing power to the electronic components. The reed switch may, for example, be an RA, RS or RM series reed switch manufactured by Soway Tech Limited.

FIGS. 10-12 show additional details of the wiper assembly 114. A spring (106) applies an upward force on the round follower 104. The round follower 104 presses against the ammunition round 102 held in the magazine, moving upward in the magazine body 170 as the rounds 102 are fired by the firearm. A sensor 108 is positioned against an inside surface 112 of the magazine rear sidewall 110. The sensor extends linearly along the sidewall at least between the highest and lowest points through which the round follower 104 travels during operation of the magazine between empty and full.

In the embodiments illustrated in FIGS. 10-12, a cavity 190 is formed in the round follower 104 adjacent a lower surface 192 of the follower. The cavity 190 faces the sensor and may be a cylindrical bore. A spring 176 is placed into the cavity 190, and a plunger 118 is placed into the cavity against the spring such that the plunger is held in contact with the sensor with sufficient pressure to activate the sensor.

FIGS. 13-15 illustrate embodiments of the present invention in which the magazine is loaded with three rounds 102. Having three rounds in the magazine, the round follower 104 is pushed downward a certain distance from its topmost position, and the cavity 190 of the round follower lines up with a portion of the sensor such that the plunger (118) presses against the sensor 108 at a distance 192 from the top end of the sensor. Operation of the sensor provides a signal indicative of this distance to the electronic components of the electronics enclosure 116. For example, if a membrane potentiometer is used, the sensor provides an analog electrical signal to the ADC that corresponds to the distance from the top end of the sensor. The position of the plunger corresponds to a specific linear distance indicative of the number of rounds remaining in the magazine, three in this example. The ADC converts this analog signal to a digital signal, and the DSP 136 converts the signal into information that is indicative of how many rounds remain in the magazine. This information is passed to the transmitter 144 that sends the information to the display assembly. The display 162 of the display assembly then presents the information in a manner that is readable by the shooter. In this example, the display 162 is a screen that shows the number 03, indicating that three rounds remain.

FIGS. 16-18 illustrate embodiments of the present invention in which the magazine is empty. The magazine being empty, the round follower 104 is at its topmost position, and the cavity 190 of the round follower lines up with a portion of the sensor such that the plunger (118) presses against the sensor 108 at a distance 194 from the top end of the sensor. This distance 194 is less than the distance (192) when three rounds were present in the magazine. As described with respect to FIGS. 13-15, Operation of the sensor provides a signal indicative of this distance to the electronic components of the electronics enclosure 116. This signal is appropriately processed, and information is passed to the transmitter 144 that sends the information to the display assembly. The display 162 of the display assembly then presents the information in a manner that is readable by the shooter. In this example, the display 162 is a screen that shows the number 00, indicating that no round remains.

This application describes various exemplary embodiments having various electronic components. The components shown and described herein may include more or fewer components, and each of the referenced components may itself include a single, separate component, may include multiple or may include multiple components mounted together or integrally formed. Alternatively, a single electronic component may provide the functionality of multiple components described herein or a the functionality of a single component as describe may be performed by multiple components.

The firearms and components of the present invention have been described herein as having certain exemplary features. However, it is not intended that the invention be limited to these illustrative embodiments, and it is contemplated that the present invention may include any compatible feature or configuration as would be understood by one of ordinary skill in the art. 

What is claims is:
 1. A round counter for a firearm comprising: a magazine adapted to store a plurality of ammunition rounds for use in the firearm; a round follower positioned within the magazine below the plurality of ammunition rounds; a biasing member that applies an upward force on the round follower; a variable resistance sensor; a wiper that is connected with the round follower and that contacts the sensor; and a display that displays information relative to the number or ammunition rounds remaining in the magazine.
 2. The round counter of claim 1 wherein the biasing member is a spring.
 3. The round counter of claim 1 wherein the sensor is a contact sensitive variable resistance sensor.
 4. The round counter of claim 1 wherein the sensor is a linear potentiometer.
 5. The round counter of claim 1 wherein the sensor is a membrane potentiometer.
 6. The round counter of claim 5 wherein the membrane potentiometer comprises a top circuit, a circuit spacer and a bottom circuit.
 7. The round counter of claim 1 wherein the sensor is attached to an inside surface of a sidewall of the magazine.
 8. The round counter of claim 1 wherein the wiper extends from the round follower and contacts the sensor with sufficient pressure to activate the sensor.
 9. The round counter of claim 8 wherein the wiper extends from the round follower at an angle that is substantially perpendicular to a direction of movement of the round follower.
 10. The round counter of claim 8 further comprising a spring that biases the wiper to provide pressure on the sensor.
 11. The round counter of claim 1 further comprising an identification tag attached to the magazine.
 12. The round counter of claim 11 wherein the identification tag is encoded with unique identification information.
 13. The round counter of claim 1 further comprising a transmitter that transmits information to the display relating to the number of rounds remaining in the magazine.
 14. A round counter for a firearm comprising: a magazine adapted to store a plurality of ammunition rounds for use in the firearm, the magazine comprising a magazine body having a sidewall; a round follower positioned within the magazine below the plurality of ammunition rounds, the round follower moving within the magazine body as ammunition rounds are added to or removed from the magazine; a linear potentiometer attached to the magazine body sidewall; a wiper that is connected with the round follower and that contacts the linear potentiometer; one or more electronic components that receive information from the linear potentiometer relating to the position of the wiper and that transmit information relating to the number of ammunition rounds remaining in the magazine; and a display that received the information from the electronic component and displays information relative to the number or ammunition rounds remaining in the magazine in a user readable format.
 15. The round counter of claim 14 wherein the position of the wiper relative to the linear potentiometer corresponds to a specific linear distance indicative of the number of rounds remaining in the magazine.
 16. The round counter of claim 14 wherein the display is a digital numeric display.
 17. The round counter of claim 14 wherein the electronic components comprise a power source.
 18. The round counter of claim 14 wherein the electronic components comprise: an analog to digital converter that comprises an input connection that receives signals provided on an output connection of the sensor and an output connection; a digital signal processor that comprises an input connection that receives signals provided on an output connection of the analog to digital converter and an output connection; and a transmitter that comprises an input connection that receives signals provided on an output connection of the digital signal processor and transmits signals to a receiver connected with the display.
 19. The round counter of claim 18 wherein the transmitter is a wireless transmitter.
 20. The round counter of claim 14 further comprising a switch that is activated when the magazine is inserted into the firearm. 